Auxiliary intake valve

ABSTRACT

An intake valve structure for use in an internal combustion engine wherein a conventional intake poppet valve operable in the normal manner slidably carries an auxiliary intake valve in the form of a tubular poppet valve which is normally spring-biased into closed position upstream of the intake poppet valve but which can be opened by differential pressure existing between the intake manifold and the cylinder with which this intake valve structure cooperates during the time interval when the intake poppet valve is open.

United States Patent Klakulak et al. 1 1 Sept. 9, 1975 [541 AUXILIARY INTAKE VALVE 264,416 10/1949 Switzerland 4, 123/7 1 C 46.503 lZ/l929 Norway 4 123/79 C [75] Inventors: Thomas J. Klakulak, Warren; 7,44% m W49 5 U d 79 Edward D. Klomp Mt- Clcmcns -n W1 ,cr an ,l C both of Mich.

[731 Assignee: General Motors Corporation, l'

Detmin Mich Amman! li.\'ulm'm'r--Danicl J. OConnor Attorney, Agent. or FirmArthur N. Krein [22] Filed: Sept. 28, 1973 [21] Appl. No.: 401,588

[57| ABSTRACT [52] US. Cl. 123190.14; 123/79 C; 123/188 VA [5]] f FOIL 9/02 An intake valve structure for use in an internal com- [58] held gem-chm 123/9014 [88 188 hustion engine wherein a conventional intake poppet 123/188 M, 7 C. 133 S valve operable in the normal manner slidahly carries an auxiliary intake valve in the form of a tubular pop- [56l References cued pct valve which is normally springhiascd into closed UNITED STATES PATENTS position upstream of the intake poppet valve but 1 722,799 7/|929 Jones 33 9 4 which can he opened by differential pressure existing 2,191,745 2/1940 Barkcij l23/79C between the intake manifold and the cylinder with 1439.618 4/1948 Cloutier 123/79 C which this intake valve structure coopcratcs during 2,693,6[5 1/1955 Dittmann I. 123/]88 VA [hc time interval whcn the intukc poppet vulvc is 3,557,762 1/1971 Mitchell H 123/79 C Germany 123/188 VA open.

4 Claims, 3 Drawing Figures PATENIED SE? 975 AUX. VALVE S T D. VALVE TIMING STD.VALVE AUX.VALVE INTAKE TIMING ADVANCE D 60CAMSHAFT STD. VALVE l 2 3 ENGINE SPEED N (I000 RPM) AUXILIARY INTAKE VALVE This invention relates to an intake valve structure for use in internal combustion engines and, in particular to an auxiliary intake valve used in cooperation with a conventional intake poppet valve.

Intake valves for internal combustion engines are normally of the poppet type, seating against a valve seat in the head of the engine to control the flow of air from the intake manifold to a cylinder of the engine during the induction cycle for that cylinder of the engine. With this type of valve, air intake and the timing thereof is, in effect, controlled by the unseating and seating of the intake poppet valve. When using such an intake poppet valve, backflow from the cylinder into the intake manifold can occur during intake valve and exhaust valve overlap and during intake valve closure on the compression stroke.

Accordingly, the principal object of this invention is to provide an intake valve structure for use in an internal combustion engine which is operable to prevent backflow from the cylinder into the intake manifold at any time during an engine operating cycle.

Another object of this invention is to provide an intake valve structure for use in an internal combustion engine whereby the flow of induction air from the intake manifold to a cylinder is controlled by a conventional poppet valve and an auxiliary intake valve coopcrating therewith and actuated automatically by the pressure difference between the intake manifold and the cylinder of the engine.

A still further object of this invention is to reduce internally generated charge dilution in an internal combustion engine, such as a spark ignition engine, by preventing backflow of cylinder gases into the intake manifold through the use of an automatically pressureactuated valve located in the intake port for a cylinder immediately upstream of the conventional intake poppet valve for that cylinder.

These and other objects of the invention are attained by an intake valve structure which includes a conventional intake poppet valve operable in a normal manner to control the flow of induction fluid through an intake port to the cylinder of an internal combustion engine and an auxiliary valve located in the intake port upstream of the head of the intake poppet valve, this auxiliary valve being adapted to open automatically and remain open during the cylinder induction event only as long as the fluid pressure in the intake manifold exceeds the fluid pressure in the cylinder. This auxiliary valve closes and remains closed when the conventional intake poppet valve is open, if the fluid pressure in the cylinder exceeds the fluid pressure in the intake manifold. Normal operation of the conventional intake poppet valve is unaffected and either a conventional carburetor or a fuel injection system can be used with this type intake valve structure. For a better understanding of the invention, as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a sectional view ofa portion of an internal combustion engine having an intake valve structure, in accordance with the invention, positioned to control the flow of fluid through an intake port of the engine, this intake valve structure being shown in solid lines in its closed position and in broken lines in its open position;

FIG. 2 is a view similar to FIG. 1 but showing the intake poppet valve of the subject intake valve structure in an open position and showing the auxiliary valve of this structure remaining in a closed position; and

FIG. 3 is a graph showing test results of how volumetric efficiency varies with engine speed with both standard valve timing and intake timing advanced when using a conventional standard intake valve and when using an intake valve structure constructed in accordance with the invention wherein an auxiliary valve is used in cooperation with a conventional intake poppet valve.

Referring now to FIGS. 1 and 2, there is illustrated a portion of an internal combustion engine containing a cylinder head 10 having an induction passage 12 therein terminating at an induction or intake port 14 to a cylinder, not shown. Flow through the intake port 14 is controlled by an intake valve structure, in accordance with the subject invention, which includes a conventional intake valve in the form of poppet valve 16 having its valve head l8 adapted to seat against an annular valve seat 20 provided for this purpose in the cylinder head 10.

The elongated stem 22 of valve 16 is slidably journaled in a stem guide bore 24 in the cylinder head and in the axial bore 26 extending through a valve guide 28. Valve guide 28, which is of tubular configuration, is fixed at one end to the cylinder head with the bore 25 therethrough in axial alignment with bore 24, as by engagement of the external threads 28a on one end of guide 28 with the threaded bore portion 240 at one end of bore 24 in cylinder head 10.

The valve stem 22 and therefore valve 16 is reciprocated in suitable timed relation to the operation of the other components of the engine, including an exhaust valve, not shown, for the same cylinder with which intake port 14 cooperates in a known manner, not shown, to regulate the opening and closing movements of valve head 18 relative to the valve seat 20. This is conventionally done by means of a cam, not shown, effecting opening movement of the intake valve 16 against the biasing action of a conventional valve return spring, not shown.

The subject intake valve structure further includes an auxiliary intake valve which, in the embodiment illustrated, is in the form ofa tubular poppet valve 30 encircling the intake valve 16 and positioned for axial movement relative to the intake valve 16 upstream of this valve in the intake port 14. [n the embodiment shown, the auxiliary intake valve 30 includes a tubular stem 32 and an annular valve head 34 formed integral therewith, the valve head 34 having a size and configuration to closely overlie the valve head 18 of intake valve 16 in position to have the annular seating portion 34a thereon seal against the valve seat 20. It is preferred that the valve head 34 of auxiliary intake valve 30 be located in the intake port as close to the conventional intake valve 16 as possible so as to reduce to a minimum the trapped volume between this auxiliary intake valve 30 and the conventional intake valve 16.

The hollow tubular stem 32 of the auxiliary intake valve 30 includes an enlarged diameter main item portion at one end thereof adjacent to head 34 which has an internal diameter such as to slidably encircle the peripheral portion of radial flange 28c on one end of valve guide 28 opposite from the threaded end 280 thereof, and at its other end the tubular stem 32 has a reduced diameter portion 321: having an inside diameter such as to slidably encircle the peripheral portion of the main body portion 28b of valve guide 28 between the flange 28(- and the threaded end 28a thereof. A radial shoulder 32b interconnects the main stem portion of the stem with its reduced diameter portion 320.

Auxiliary intake valve 30 is normally biased in an axial direction whereby its head 34 is seated against valve seat by means of coil spring 36 encircling the body portion 28b of valve guide 28, with one end of this spring in abutment against the radial shoulder 32b of the valve stem 32 of this valve and the other end of the spring in abutment against the radial flange 286 of the valve guide 28.

Preferably the auxiliary intake valve 30 is constructed of a suitable material, such as spring steel, to provide for a minimum mass and should be arranged to have minimum sliding friction, should have durability comparable to that of a conventional intake valve and should have minimum flow area restriction under wide open conditions. Since mass and sliding friction cannot be equal to zero, the spring 36 is necessary to insure that the auxiliary intake valve 30 closes before intake valve 16 closure and prior to its reopening. Furthermore, the Spring 36 will help to effect closing of the auxiliary intake valve 30 prior to intake valve 16 closure whenever the pressure in the cylinder exceeds intake manifold pressure. Increasing the force of spring 36 beyond a predetermined desired value will hasten the closing of the auxiliary intake valve 30, but will also reduce the rate of change and maximum value of auxiliary valve area, tending to reduce volumetric efficiency of the engine.

When using an auxiliary valve 30 of the configuration as shown in FIGS. 1 and 2, the outer diameter of its head should be sufficiently less than the outside diameter of the head 18 of poppet valve 16 so that, as best seen in FIG. 1, the head 34 of the auxiliary valve will seat against the valve seat 20 a sufficient distance upstream frorn the head 18 of the valve 16, so that at all times proper seating of the valve 16 can occur to thereby prevent hot exhaust gases from contacting the auxiliary valve 30.

In a conventional engine using a conventional intake poppet valve only, valve timing is primarily determined by high-load, high-speed requirements. In order to provide large valve port flow areas the valve lift must be large; this means that, in consideration of valve train loading, the intake valve must open well before the piston reaches top dead center and when the cylinder pressure is well above intake manifold pressure. Thus, exhaust backflow from the cylinder into the intake manifold occurs. Also in the conventional engine and in the interest of high speed performance, intake valve closing does not occur until well after bottom dead center. Therefore, at low speeds some of the diluted charge already in the cylinder is pushed back out of the cylinder into the intake manifold during the compression stroke.

In the operation of the subject intake valve structure, during engine operation, the conventional intake valve 16, such as the poppet valve 16 shown, would be opened to the position shown by broken lines in FIG. 1 and full lines in FIG. 2 in a conventional manner. in general, in current automotive engines the intake valve 16 would be open when the pressure in the cylinder, not shown, with which it cooperates, is well above in take manifold pressure and the pressure in induction passage 12, particularly at part load operating conditions. However, with the auxiliary valve 30 still seated as shown in FlG. 2, backflow through the now opened valve 16 port into the intake manifold will not occur, since this auxiliary valve will remain seated against the valve seat 20 blocking flow through the inlet port 14 until such time as the force caused by the difference between the higher intake manifold pressure and the lower cylinder pressure acting on the surfaces of the auxiliary valve 30 and in particular its head 34 exceeds the force exerted by the spring 36 to effect opening of this valve. When this occurs, the head 34 of the auxiliary valve 30 lifts off the valve seat 20 and will be forced, by this differential force, into an open position relative to the valve seat, opening movement being limited by engagement of valve 30 with the head 18 of the intake valve 16, as shown in broken lines in FIG. 1.

Also in current automotive engines, the intake valve 16 does not completely close until the piston, not shown, is about half-way up on the compression stroke in the cylinder, not shown, with which the intake valve cooperates. Before the intake valve 16 closes completely, the pressure in the cylinder will exceed that in the intake manifold and in induction passage 12, and backflow will occur during this time over most of the engine operating range. This problem is most serious at low speeds. However, with the subject intake valve structure, as this occurs, the pressure in the cylinder, being greater than the pressure in the intake manifold or in the induction passage 12, together with the biasing action of the spring 36, will cause the auxiliary valve 30 to again reseat to the position shown in H0. 2 while the intake valve 16 is still unseated. Closure of the auxiliary valve 30 prior to the closure of the intake valve 16 will thus prevent backflow from the cylinder into the induction passage 12 and from there into the intake manifold, not shown. The intake valve 16 would then be closed in a conventional manner so that sealing against high cylinder pressures, for example as during combustion, is accomplished by the conventional inlet valve 16. As can be seen, the auxiliary intake valve 30 need only seal during the time the conventional intake valve 16 is open and cylinder pressure exceeds intake manifold pressure.

As a result of eliminating backflow through the use of the subject intake valve structure, the fuel-air charge in the intake manifold of the engine is not diluted with residual gas from the cylinder prior to emittance of a charge into the cylinder. Furthermore, by the elimination of backflow, carburetion and fuel cylinder to cylin der distribution will be improved. That is, by the use of the auxiliary valve 30 with the conventional poppet valve 16 the large higher-than-manifold pressure pulses which would normally reach the carburetor a d tend to cause backflow and influence the charging process of other cylinders will be eliminated.

ln tests conducted on a commercially available engine over a range of operating speeds, first using a conventional inlet valve and then using the engine as modifled by the subject inlet valve structure, including the inlet valve 16 and auxiliary valve 30 as shown, test results have indicated that the residual gas fraction at wide open throttle would be significantly reduced when the engine was operating with the subject inlet valve structure as compared to operation with the conven tional inlet valve only and. as shown bv the graph illus tratcd in FIG. 3, the volumetric et'ticicnu N, of the can gine was appreciably greater at all speeds tested during wide open throttle operation of the engine when the subject valve structure was used. as shown by the curves identified by the term Al X VALVE" than the volumetric efficiency when the engine was operating with only a conventional intake valve, as shown by the curves identified by the term "STD. VALVE. As can be seen by the graph illustrated in FIG 3, with standard valve timing the volumetric efficiency was improved about 6 percent over the speed range tested by the use of the subject inlet valve structure as compared to the volumetric efficiency obtained by the use of a standard inlet valve only.

A more impressive result is the performance of the engine with the subject inlet valve structure when the intake event was advanced 6t) camshaft degrees. as by means of a variable cam timing arrangement used on the engine. This cariablc cam timing arrangement is not shown or described since it forms no part of the subject invention As seen by the bottom set of curves in FIG. 3, the volumetric efficiency of the engine was substantially greater under this mode of operation, as described. when the engine was operated with the subject intake valve structure as compared to operation with a conventional valve only. However. during this mode of operation. the engine would tire only sporadically when operated with only a standard. conventional intake valve. very likely because of the excessively large residual gas fraction caused by the extreme intake-exhaust valve overlap Since the auxiliary valve functions in the manner previously described to prevent backflow.

engine operation was very smooth with the subject intake valve structure; that is, valve 16 and auxiliary valve 30. was installed in the engine.

What is claimed is:

1. In a internal combustion engine having a cylinder head with an induction passage therein for the passage of induction fluid to a cylinder of the engine. said induction passage including an inlet port having a beveled annular valve seat therein positioned closely adjacent to the cylinder, an intake valve structure positioned in said inlet port for controlling flow between said induction passage and the cylinder, said intake valve structure including an intake valve having a stem and an annular head concentric therewith. said head having an annular beveled seating portion for engagement with said valve seat. stern guide means in said cylinder head. said stem being slidably journaled in said stem guide means with the free end thereof extending outward from said stem guide means in position to be. actuated by a valve actuator mechanism including a cam whereby said intake valve can be reciprocally moved in timed relation to the operation of other components of the engine from a position in which said seating portion of said head is in sealing engagement with said valve seat to a position in which said head is unseated with respect to said valve seat. an auxiliary intake valve means positioned upstream of said intake valve in said induction passage for movement relative to said inlet port between a first position with said auxiliary intake valve seated against said valve seat to block flow through said inlet port and a second position to permit flow through said inlet port and. spring means operably engaging said auxiliary intake valve means to normally bias said auxiliary intake valve means to said first position.

2. in an internal combustion engine according to claim I wherein said stem guide means includes a tubular stem guide fixed to said cylinder head in position to extend into said induction passage adjacent to said inlet port. and wherein said auxiliary intake valve means is a tubular poppet valve positioned to slidably encircle said stem guide and said stem of said intake valve. said tubular poppet valve having an annular head adapted to overlie said head of said intake valve and a tubular stem concentric therewith positioned to slidably encircle said stem guide and, wherein said spring means is positioned to encircle said stern guide within said tubular stem of said poppet valve with one end of said spring operatively fixed to said stern guide and the other end of said spring engaging said tubular stem.

3. An intake valve structure in an internal combustion engine having a cylinder and a cylinder head with an induction passage therein, said induction passage terminating at an inlet port with an annular valve seat therein adjacent to said cylinder. said intake valve structure including an intake poppet valve having a stem and an annular head concentric therewith. said head having an annular seating portion of a complemcntary shape to the valve seat in the inlet port, said stem being slidably journaled in said cylinder head with the free end thereof extending outward from said cylinder head for actuation by a valve actuator mechanism including a cam whereby said intake poppet valve can be reciprocated in timed operation to the operation of other components of the engine between a position in which said seating portion of said head is in sealing engagement with said valve seat to a position in which said head is unseated with respect to said valve seat. an auxiliary intake valve means adapted to be positioned upstream of said head of said intake poppet valve in the induction passage for movement relative to said valve seat between a first position to block flow through said inlet port and a second position to permit flow through said inlet port and, spring means operatively connected to said auxiliary intake valve means and to said cylinder head to normally bias said auxiliary intake valve means to said first position.

4. An intake valve structure according to claim 3 further including a tubular stem guide secured at one end to said cylinder head in position in the induction passage to slidably receive said stem. said tubular stem guide having a radial flange at its opposite end. and wherein said auxiliary intake valve means is a tubular poppet valve having a stepped tubular stem. slidably encircling said tubular stem guide and said stem. and a head portion also encircling said stem adjacent to said head in position to seat on said valve seat upstream of said head of said intake poppet valve, and wherein said spring means is positioned around said tubular stem guide with one end of said spring means engaging said tubular stem of said tubular poppet valve and the other end of said spring means engaging said radial flange of said tubular stem guide. 

1. In a internal combustion engine having a cylinder head with an induction passage therein for the passage of induction fluid to a cylinder of the engine, said induction passage including an inlet port having a beveled annular valve seat therein positioned closely adjacent to the cylinder, an intake valve structure positioned in said inlet port for controlling flow between said induction passage and the cylinder, said intake valve structure including an intake valve having a stem and an annular head concentric therewith, said head having an annular beveled seating portion for engagement with said valve seat, stem guide means in said cylinder head, said stem being slidably journaled in said stem guide means with the free end thereof extending outward from said stem guide means in position to be actuated by a valve actuator mechanism including a cam whereby said intake valve can be reciprocally moved in timed relation to the operation of other components of the engine from a position in which said seating portion of said head is in sealing engagement with said valve seat to a position in which said head is unseated with respect to said valve seat, an auxiliary intake valve means positioned upstream of said intake valve in said induction passage for movement relative to said inlet port between a first position with said auxiliary intake valve seated against said valve seat to block flow through said inlet port and a second position to permit flow through said inlet port and, spring means operably engaging said auxiliary intake valve means to normally bias said auxiliary intake valve means to said first position.
 2. In an internal combustion engine according to claim 1 wherein said stem guide means includes a tubular stem guide fixed to said cylinder head in position to extend into said induction passage adjacent to said inlet port, and wherein said auxiliary intake valve means is a tubular poppet valve positioned to slidably encircle said stem guide and said stem of said intake valve, said tubular poppet valve having an annular head adapted to overlie said head of said intake valve and a tubular stem concentric therewith positioned to slidably encircle said stem guide and, wherein said spring means is positioned to encircle said stem guide within said tubular stem of said poppet valve with one end of said spring operatively fixed to said stem guide and the other end of said spring engaging said tubular stem.
 3. An intake valve structure in an internal combustion engine having a cylinder and a cylinder head with an induction passage therein, said induction passage terminating at an inlet port with an annular valve seat therein adjacent to said cylinder, said intake valve structure including an intake poppet valve having a stem and an annular head concentric therewith, Said head having an annular seating portion of a complementary shape to the valve seat in the inlet port, said stem being slidably journaled in said cylinder head with the free end thereof extending outward from said cylinder head for actuation by a valve actuator mechanism including a cam whereby said intake poppet valve can be reciprocated in timed operation to the operation of other components of the engine between a position in which said seating portion of said head is in sealing engagement with said valve seat to a position in which said head is unseated with respect to said valve seat, an auxiliary intake valve means adapted to be positioned upstream of said head of said intake poppet valve in the induction passage for movement relative to said valve seat between a first position to block flow through said inlet port and a second position to permit flow through said inlet port and, spring means operatively connected to said auxiliary intake valve means and to said cylinder head to normally bias said auxiliary intake valve means to said first position.
 4. An intake valve structure according to claim 3 further including a tubular stem guide secured at one end to said cylinder head in position in the induction passage to slidably receive said stem, said tubular stem guide having a radial flange at its opposite end, and wherein said auxiliary intake valve means is a tubular poppet valve having a stepped tubular stem, slidably encircling said tubular stem guide and said stem, and a head portion also encircling said stem adjacent to said head in position to seat on said valve seat upstream of said head of said intake poppet valve, and wherein said spring means is positioned around said tubular stem guide with one end of said spring means engaging said tubular stem of said tubular poppet valve and the other end of said spring means engaging said radial flange of said tubular stem guide. 